GB2304465A

GB2304465A - Slot antenna device

Info

Publication number: GB2304465A
Application number: GB9622162A
Authority: GB
Inventors: Shunsuke Koyama; Teruhiko Fujisawa; Norio Hama
Original assignee: Seiko Epson Corp
Current assignee: Seiko Epson Corp
Priority date: 1993-03-17
Filing date: 1994-03-17
Publication date: 1997-03-19
Anticipated expiration: 2014-03-17
Also published as: GB2304464B; GB2304464A; GB2304465B; GB9622162D0; GB2304466A; GB9622156D0; GB9622165D0; GB2304466B

Description

2304465 1 SLOT ANTENNA DEVIC The present invention relates to antenna

devices for portable apparatus, such as wireless sets used in pagers and others and to apparatus including such antenna devices. More particularly, but not exclusively, the present invention relates to antenna devices of the type housed in a case.

Conventionally, portable wireless devices, such as portable telephones, have employed a monopole antenna, or an inverted F type antenna, while devices, such as pa( gers, have employed a ferrite antenna, a small-loop antenna, or a plate type loop antenna. The radiation efficiency or reception efficiency of an antenna, however, is determined by the ratio of the wavelength of the electric radiation employed and the size of the antenna. Accordingly, in the case of an antenna small enough to be employed in a pager, a high frequency must be used and it is impossible to make a pa,(,, ,er which can be used in the FM band. Because a loop antenna, for instance, needs to have a large aperture in order to be usable in the FM band, it cannot be employed in a pager.

Taking the above-mentioned problems into consideration, an object of the present invention is to provide a slot antenna device which can be miniaturised and thinned to be housed in a case, yet maintaining high transmission and reception performance, and wireless apparatus employing this antenna device. This is done by improving the configuration of an antenna body and circuit board put in wireless apparatus using an antenna.

According to one aspect of the present invention, there is provided a device comprising an electrically conductive member formed with a slot therethrough to form a slot antenna, and a circuit board carrying wireless circuitry for connection to the antenna, wherein the electrically conductive member is contiguous with the surface of the circuit board.

2 According to another aspect of the present invention, there is provided a device comprising a circuit board carrying wireless circuitry for connection to an antenna and an electrically conductive member with a slot to form a slot antenna, both formed in the circuit board as a single conductive pattern.

Other aspects of the present invention are to be found amongst the appended claims. How the invention may be carried into effect is hereinafter particularly described with reference to the accompanying drawings, in which:- Figure I(a) schematically illustrates the structure of an antenna body in a first embodiment of antenna device; Figure l(b) illustrates the configuration of the antenna body and a circuit board in the embodiment of figure I(a); Figure 2 is a block diagram of a super heterodyne receiver circuit with which the embodiment of antenna device illustrated in Figure l(a) is used; Figure 3 is a block diagram of a wide-band receiver circuit with which the embodiment antenna device illustrated in figure l(a) is used; Figure 4(a) is an explanatory diagram of the antenna device illustrated in figure I (a); Figure 4(b) is a graph of the directivity characteristics; Figure 5 illustrates the configuration of an antenna body and circuit board in a t:' first variant of the first embodiment of device; Figure 6 illustrates the configuration of an antenna body and a circuit board in a second variant of the first embodiment of antenna device; Figure 7 illustrates the structure of an antenna body for a third variant of the first embodiment of antenna device; Figure 8 schematically illustrates the configuration of an antenna body and a circuit board in a second embodiment of antenna device according to the invention; Figure 9 illustrates the structure of an antenna body in a first variant of the r) second embodiment of antenna device according to the invention; 3 Figure 10 illustrates the configuration of an antenna body and a circuit board in a second variant of the second embodiment of antenna device according to the invention; Figure 11 illustrates the configuration of an antenna body and a circuit board in third variant of the second embodiment of antenna device according to the invention; Figure 12 illustrates the configuration of an antenna body and a circuit board in fourth variant of the second embodiment of antenna device according to the invention; Figure 13 illustrates the structure of an antenna body in a third embodiment of antenna device according to the invention; Figure 14 illustrates the structure of an antenna body in a first variant of the third embodiment of antenna device according to the invention; Figure 15 illustrates the configuration of an antenna body and a circuit board in a fourth embodiment of antenna device according to the invention; Figure 16 illustrates the configuration of an antenna body and a circuit board in a first variant of the fourth embodiment of antenna device according to the invention; Figure 17 illustrates diagrammatically the structure and configuration of an antenna body and circuit board in a fifth embodiment of antenna device; Figure 18 is a graph showing the directivity characteristics of the device illustrated in Figure 17; Figure 19 illustrates diagrammatically the structure and configuration of an antenna body and circuit board in a first variant of the fifth embodiment of antenna device; Figure 20(a) illustrates the operation of the antenna device shown in figure 17; C Figure 20(b) illustrates the operation of the antenna device shown in figure 19; Figure 21 illustrates the configuration of an antenna body and a circuit board in C 0 a second variant of the fifth embodiment of antenna device; Figure 22 illustrates the structure and configuration of an antenna body and a c circuit board in a third variant of the fifth embodiment of antenna device; 4 Figure 23 illustrates the configuration of an antenna body and a circuit board in a fourth variant of the fifth embodiment of antenna device; Figure 24(a) illustrates the structure and configuration of an antenna body and circuit board in a fifth variant of the fifth embodiment of antenna device; Figure 24(b) is a graph showing the directivity characteristics of the device of figure 24(a); Figure 25 is an exploded view of a wristwatch-type portable wireless set loaded with the antenna device illustrated in figure 24(a) viewed from the back; Figure 26 is an exploded view, similar to figure 25, of a portable wireless set loaded with a sixth variant of the fifth embodiment of antenna device; Figure 27(a) illustrates an unbalanced circuit formed in the portable wireless set illustrated in Figure 26; Figure 27(b) illustrates a balanced circuit formed in the portable wireless set illustrated in figure 26; 0 Figure 28 illustrates the structure of an antenna body in a sixth embodiment of antenna device; Figure 29 illustrates the structure of an antenna body in a first variant of the sixth embodiment of antenna device; Figure 30 is a circuit diagram of an antenna circuit and a wireless set circuit for the device illustrated in Figure 29; Figure 31 illustrates the structure of an antenna body in a second variant of the sixth embodiment of antenna device; Figure 32 is an exploded view of the antenna body illustrated in Figure 3 1; Figure 33 illustrates the structure of an antenna body in a seventh embodiment of antenna device; Figure 34 is a circuit diagram of an antenna circuit and a wireless set circuit for the antenna device illustrated in Figure 33; Figure 35 illustrates the structure and configuration of an antenna body and circuit board in an eighth embodiment of antenna device; b Figure 36 illustrates the structure and configuration of a first variant of the eighth embodiment of antenna device; Figure 37 illustrates the structure and configuration of a second variant of the eighth embodiment of antenna device; Figure 38 illustrates the structure and configuration of a third variant of the eighth embodiment of antenna device; Figure 39 illustrates the structure of an antenna body in a ninth embodiment of device; Figure 40 illustrates the structure of an antenna body in a first variant of the ninth embodiment of device; and, Figure 41 illustrates the structure of an antenna body in a second variant of the ninth embodiment of device.

In the following description of the antenna device embodiments, each antenna body is intended to be mounted or formed in a case of a portable antenna-using device housed in a case, such as a pager, a mobile telephone, a radio, a transceiver, a portable TV or the like housed in a case, such as a first embodiment.

Reference is also made to the article entitled "A Study on Small Slot Antenna for Wrist Watch Type Portable Radio Equipment" published in The Institute of Electronics Information and Communication Engineers published on 17th August 1993.

An antenna body I la (fig. I (a)) of a portable wireless set has a slot 112 formed longitudinally in the centre of an electrically conductive plate 111, and functions as a slot antenna. The electrically conductive plate 111 has terminals 11 la to 11 Id projecting from the edges of the slot 112 with their surfaces in the planes thereof. The antenna body 1 la with such a structure is contained in a case for a wireless set together with a circuit board 12 (fig. l(b)) which is copper-clad glass epoxy laminate and which carries the wireless set circuitry through which transmission or reception is performed.

The circuit board 12 is inserted in the slot 112 of the antenna body 11 a as shown in Figure l(b). The antenna body I la and the circuit board 12 are in a case for a wireless set. As each of the terminals I I la to I I Id engages a surface of the circuit 0 6 board 12 in this state, the antenna body 1 la and the circuit board 12 are held together by fixing each of the terminals 111 a to 111 d on a conductor pattern of the circuit board 12, by soldering or the like.

On the circuit board 12, the wireless set circuitry includes a tuning capacity element, a feed or receiving circuit and so on. The terminals 111 a and 111 b are electrically connected with the tuning capacity element, and the feed or receiving circuit is electrically connected with the terminals 111 c and 111 d. If the feed or receiving circuit is an unbalanced circuit, either the terminal 11 l c or the terminal 11 l d is held at ground electric potential. On the other hand, if the feed or receiving circuit is a balanced circuit, the terminals 111 c and 111 d are each electrically connected with a balanced input terminal of the circuit. In order to realise the impedance matching of the antenna body 1 la and the wireless set circuit, it is necessary to space the position of the feed point of the antenna body 1 la from the connection position of the tuning capacity element. Therefore, the terminals 11 la and 11 1b and the terminals 11 lc and 11 ld are formed at relatively spaced positions, and the distance is determined by the electrical characteristics of the antenna body 11 a and the wireless set circuit and so on.

If the portable wireless set in which the antenna body 1 l a is put is a fixed frequency receiver, (Figure 2) a single super heterodyne circuit 120 is constituted in the wireless set circuitry. In this circuit, the receiving frequency in the antenna body 1 la is selected by its own electrical characteristics and those of the tuning capacitance element 121 connected with the antenna body 11 a across the slot 112. The tuning capacitance element 121, is connected to the input of a connection circuit 122 and the connection circuit 122 to an amplification circuit 123. The amplification circuit 123 is connected to a frequency conversion circuit 124 which converts the frequency of received signals based on signals from an oscillating circuit 126. The circuit 124 is connected to a demodulating circuit 125 which is designed to demodulate the received signals, the C frequency of which was converted.

If a wireless set in which the antenna body 1 la is put is a wide band receiver with wide frequency range, (figure 3) for instance, a wide band receiving circuit 130 7 with wide frequency range is formed in the wireless set circuitry. In this circuit, the receiving frequency of the antenna body 11 a is selected by its own electrical characteristics and those of a varactor diode 131 with tuning capacity elements (131a, 131b) connected across the slot 112. The varactor diode 131 is connected through a connection circuit 132 to an amplification circuit 133, whose output is to a frequency conversion circuit 134 which converts the frequency of received signals based on the signals from an oscillating circuit 136. The circuit 134 is connected to a demodulating circuit 135 to demodulate the output signals formed. A level detection circuit 137 detects the signal level after frequency conversion, and a tuning voltage build-up circuit 138 controls the voltage applied to between the tuning capacity elements 131a, 131b in such a way as to maximise the signal level based on the detection result. The anode of the varactor diodel31 can be grounded without disturbing the balance by holding one end of the antenna body 1 la at ground electric potential.

In such portable wireless apparatus, if the slot 112 in the antenna body 1 la is disposed in the XY plane direction (figure 4(a)) it shows a figure-of-eight directivity to C a perpendicular polarisation (figure 4(b)). This configuration is the same as the directivity characteristics which a dipole antenna placed level shows to a level polarization. That is, the antenna body 1 la functions as an antenna sensitive to magnetic components in the longer direction of the slot 112.

0 In this embodiment, the circuit board 12 is inserted in the slot 112 of the antenna body 1 la. This means that dielectric material such as glass epoxy resin with a dielectric constant of substantially 4.4 is filled in the slot 112. Accordingly, received signals are apparently shortened in proportion to the square root of dielectric constant of the dielectric material in the slot 112, and the effective length of the antenna body 1 la is increased. As a result, signals of long wavelength can be received even if the antenna body 1 la is miniaturised and thinned. Conversely, if the received signals are to have the same wavelength, the antenna body 1 la can be miniaturised and thinned. Accordingly, a portable wireless set can be made as a portable notebook-like device or 0 can be contained inside a wristwatch case.

8 Though in this embodiment the slot 112 is formed by cutting out the centre of the electrically conductive plate 111, it is possible to bend metal wire material and to use the inside as the slot 112. Further instead of holding together firmly the terminals 111 a to 111 d by fixing and connecting the antenna body 11 a and the circuit board 12, it is possible to solder the inner peripheral edges of the slot 112 of the electrically conductive plate 111 directly on conductor patterns of the circuit board 12.

First variant of the first embodiment In a first variant (Fig. 5) of the first embodiment, an antenna body 1 lb is made from an electrically conductive plate 111 with a slot 112. The electrically conductive plate 111 is bent at a right angle along a line transverse to the slot 112 at a bend 113, to form an L-shape having a portion 1 10a extending in the Y direction and a portion 1 10b extending in the X direction. A circuit board 12 of copper-clad glass epoxy laminate in which a wireless set circuit is formed is inserted in the slot 112 which opens in two directions. As in this variant, the electrically conductive plate 111 does not have terminals, the inner peripheral edges of the slot 112 of the electrically conductive plate 111 are directly soldered to conductor patterns on the circuit board 12.

In the antenna body 1 lb constituted in this way, as it is bent in an L shape, the slot 112 opens in two directions. Accordingly, the antenna body 1 lb in this variant has high sensitivity to both X and Y directions. As the antenna body 1 lb can detect both vertical polarisation and horizontal polarisation with the circuit board 12 as a standard face, the antenna body 1 lb can detect magnetic components and can also detect electrical components perpendicular to the magnetic components at right angles, thus giving high sensitivity.

The antenna body 1 lb with the bent electrically conductive plate 11, can be lengthened within the space the circuit board 12 occupies, therefore it can receive electromagnetic waves in the frequency band of relatively long wavelength.

In this variant, the ends of the antenna body 1 lb project around the outer periphery of the circuit board 12. It is possible to contain the antenna body 1 lb completely within the circuit board 12 without changing the configuration and size of C 9 the antenna body 11 b and the slot 112 by forming the edges of the circuit board 12 notches 12a where the end of the antenna body 1 lb is held, as shown in dotted lines in figure 5. Alternatively, the antenna body 1 lb can be made in two parts on the surface and back of the circuit board 12 connected at their ends by through-holes in the circuit board 12.

Such a structure can also be applied to the first embodiment and to its variants described hereinafter.

Second variant of the first embodiment In a second variant (Fig. 6) of the first embodiment, an antenna body 11 c is formed from an electrically conductive plate 111 with a slot 112. The plate 111 is bent at right angles along lines transverse to the slot 112 to form bends 113a and 113b, so that the plate 111 is of U-shape, having a portion 1 10a extending in the Y direction, a portion 1 10b extending in the X direction, and another portion 1 10c extending in the Y direction.

A circuit board 12 in which wireless set circuitry is formed is inserted in the slot 112 of the antenna body 1 lc. In this variant, the electrically conductive plate 111 does not have terminals and the inner peripheral edges of the slot 112 of the electrically conductive plate 111 are directly soldered to conductive patterns on the circuit board 12.

As the antenna body 1 lc formed in this way is bent in two places, the antenna body can be lengthened further without enlarging the circuit board 12. Accordingly, 0 the antenna body 1 lc is appropriate for transmitting or receiving electromagnetic waves in the frequency band of relatively long wavelength. Moreover, because of the disposition of the antenna body 11 c around the circuit board 12, the latter resists disengagement from the antenna body 1 lc, even when impact stresses are applied.

In this variant, if the antenna body 1 lc is placed around the outer peripheral edge of the circuit board 12, the antenna body 11 c can be lengthened more and is advantageous in transmitting or receiving electromagnetic waves in the frequency band of relatively long wavelength. As tuning frequency is determined by the length of t 0 periphery of the slot 112, the len ath of the antenna body 11 c and the length and/or width of the circuit board 12 are selected according to the tuning frequency.

Third variant of the first embodiment In a third variant (Fig. 7) of the first embodiment, an antenna body 11 d is formed from an electrically conductive plate 111 bent at four bends to have four parts 1 13a, 11 3b, 1 13c and 1 13d. The electrically conductive plate 111 is bent inward at right angles along lines transverse to a slot 112 in the plate 111 in a plane direction at each bend to form an approximately rectangular plane configuration. In this variant, a circuit board (not shown) in which wireless set circuitry is formed is inserted in the slot 112.

The antenna body 1 l d formed in this way is bent in four places, therefore the antenna body 1 ld can be further lengthened without enlarging the circuit board. The antenna body 1 ld can be fixed firmly on the circuit board. The antenna body 1 ld can be made fully rectangular or ring-shaped by connecting ends 111 e and 111 f. In this C C case, the length of the slot 112 is determined according to the frequency and wavelength c) of electromagnetic waves to be transmitted or received.

Second embodiment In a second embodiment (Fig. 8) of antenna body and circuit board, an antenna body 21a of a portable wireless set with a slot antenna device, has a lengthwise slot 212 C in the crosswise centre of an electrically conductive plate 211, and thus functions as a slot antenna. The electrically conductive plate 211 has four terminals 21 la to 21 ld projecting in a common plane from the outer peripheral edges thereof. The antenna body 21a with such a structure is contained in a case for a wireless set together with a circuit board 22 of copper-clad glass epoxy laminate, in which wireless set circuitry is formed by which transmission or reception is performed. The antenna body 21a is placed parallel to the circuit board 22 in a case for a wireless set. In this state, by soldering each of the terminals 211 a to 21 ld on a conductor pattern of the circuit board 22, the antenna body 21a is fixed on the circuit board 22 and is electrically connected 11 with a tuning capacity element and the wireless set circuitry formed on the circuit board 22.

The antenna body 21a constituted in this way, being extremely thin, is appropriate for being put in a thin portable wireless set, a radio, a pager, a mobile telephone, a portable TV or the like. As the conductor pattern formed in the circuit board 22 functions as a reflecting plate at the back of the antenna body 21a, the antenna body 21a has high sensitivity to electromagnetic waves from the top of the antenna body 21a.

In this second embodiment, the terminals 21 la to 21 ld need not be established; in which case, the electrically conductive plate 211 is directly soldered to the conductor pattern of the circuit board 22. In this case, the tuning capacity element may be placed on the outer peripheral side of the electrically conductive plate 211, or on the top of the slot 212 or the electrically conductive plate 211. First variant of the second embodiment In a first variant (Fig. 9) of the second embodiment, an antenna body 21b has four terminals 21 le to 21 1h projecting downwardly from the inner peripheral edge of the slot 212, which terminals are soldered on the conductor pattern of the circuit board (not shown). In this case, a gap can be formed between the circuit board and the antenna body 21b, so that a circuit element can be mounted between the circuit board and the antenna body 21b. Thus a miniaturisation of the circuit board can be realised by making use of the gap between the antenna body 2 lb and the circuit board as a space for mounting parts.

Second variant of the second embodiment In a second variant (Fig. 10) of the second embodiment, an antenna body 21c is formed from an electrically conductive plate 211 with downwardly projecting terminals 211e to 211h and an end 210 bent so as to project downwardly. The antenna body 21c is mounted on a circuit board 22 and the terminals 21 le to 21 1h are soldered to electrically conductive patterns on the circuit board 22. The end 210 may also be soldered to such a conductive pattern.

12 In this way, it is possible to mount parts between the antenna body 21 c and the circuit board 22 and the bond strength between body and board is improved. In the antenna body 21c, both of the detection of magnetic components by a mode as a slot antenna and the detection of electric components by a mode as an inverted F type antenna can be carried out by holding the conductor pattern on which the end 2 10 is soldered at ground electric potential and by adjusting the position of a feed point to the antenna body 21c by selection of the formation positions of the terminals 21 le to 21 1h.

Third variant of the second embodiment In a third variant (Fig. 11) of the second embodiment, an antenna body 21d is formed from an electrically conductive plate 211 with a slot 212. the plate 211 is bent at two places 213a, 213b, along lines transverse to the slot 212 and at right angles. Thus, the electrically conductive plate 211 has a top 210a extending in the X direction, a side 210b extending in the Z direction and a bottom 210c extending in the X direction. The antenna body 21d is mounted on a circuit board 22 with the top 210a and bottom 210c parallel to the board. The circuit board 22 is held between the top 210a and the bottom 210c. The electrically conductive plate 211 and the circuit board 22 can be electrically connected by direct soldering, or by making use of terminals formed on the plate 211 as in the second embodiment or first variant thereof.

The antenna body 21d constituted in this way can be lengthened within the space which the circuit board 22 occupies. The antenna body 21d has a slot 212 both on the surface and the back of the circuit board 22, and a conductor pattern formed in the circuit board 22 functions as a reflecting plate to the antenna body 21d both at the surface and the back. Hence the antenna body 21d has high sensitivity to both the top and the bottom.

Fourth variant of the second embodiment.

If a gap in which to mount parts is to be secured between the antenna body and the circuit board 22, as in the second variant of the second embodiment, this is achieved in a fourth variant (Fig. 12) of the second embodiment by bending the plate 211 at two additional places 213 c and 213d to form ends 210d and 210e which project towards the 13 circuit board 22. In this case, parts can be mounted between the antenna body 21e and the circuit board 22, and the antenna body 21e can be firmly fixed on the circuit board 22 and can be electrically connected with the circuit board 22 by soldering the ends 210d and 210e of the antenna body 21e on a conductor pattern of the circuit board 22.

Third embodiment In a third embodiment (Fig. 13) of antenna device for a portable wireless set, an antenna body 2 1 f is formed of an electrically conductive plate 211, bent in two places 213a and 213b to form a top 210d, a side 210e and a bottom 210f. A slot 212 is formed only in the top 210d. The top 210d extends in the X direction, the side 210e extends in the Z direction and the bottom 210f extends in the X direction. The side 210e and the bottom 210f do not have a slot.

The bottom 210f forms a reflecting plate for the slotted top 210d. Hence, high sensitivity to electromagnetic waves is achieved from the top.

Whilst the antenna body 21f may be mounted on a circuit board with the top and bottom parallel to the plane thereof, it will be appreciated that a circuit board in which wireless set circuitry is formed may be inserted in the slot 212, as in the first embodiment, so as to obtain the same effect as when the slot 212 is filled with dielectric material.

If the circuit board is placed between the top 2 1 Oa and the bottom 2 1 Oc, it is preferred to apply electrically ground potential to the bottom 210c.

The antenna body 21f can be composed of separate top, side and bottom parts by connecting such parts by screws, bolts or the like.

First variant of the third embodiment In a first variant (Fig. 14) of the third embodiment, an antenna body 21g comprises an electrically conductive plate 211 in which a slot 212 is formed, dielectric material 215 and a reflecting plate 214. The dielectric material 215 fills the space between the plates 211 and 214. The slot 212 of the electrically conductive plate 211 may also be filled with the dielectric material 215 or a circuit board inserted. Accordingly, the wavelength of electromagnetic waves received by the antenna body 0 0 14 2 1 g can be apparently shortened, and the antenna can respond to relatively long wavelength even if the slot 212 is short. The reflecting plate 214 serves to improve the sensitivity from the top side.

The antenna body 2 lg formed in this way can be formed by adhering the electrically conductive plate 211 and the reflecting plate 214 on the top and bottom of the dielectric material 215 moulded in a fixed configuration. In the antenna body 21g, the electrically conductive plate 211 and the reflecting plate 214 can be electrically connected along the side of the dielectric material 215.

Second variant of the third embodiment In a second variant of the third embodiment, the antenna body 21g (Fig. 14) can be formed from theelectrically conductive plate 211 and the reflecting plate 214, and the dielectric material 215 can be replaced by a circuit board 22. For this, a two-sided printed board of copper-clad glass epoxy laminate is employed as the circuit board, and the electrically conductive plate 211 in which the slot 212 is formed as a conductor pattern by patterning a metal (e.g. copper) layer on the surface of the board, whilst at the back of the circuit board, the reflecting plate 214 is formed as a conductor pattern in an area aligned with and spaced from the electrically conductive plate 211. If the antenna body 21g is formed in this way, the antenna body 21g can be manufactured easily.

It is possible to form the electrically conductive plate and the reflecting plate as conductor patterns by employing a flexible tape on both sides of which a metal layer is printed and by patterning the metal layer. In this case, as the antenna body can be freely bent, the antenna body can be placed in a narrow space, such as the inside of a wristwatch.

Fourth embodiment In a fourth embodiment (Fig. 15) of antenna device for a portable wireless set, a two-sided printed circuit board has the metal layers on both sides patterned to form an electrically conductive plate 211 in which a slot 212 is formed on one side and a reflecting plate 214 on the other to form an antenna body 21h. The main body 215 of the circuit board 22 provides the dielectric material between the plates 211 and 214. As the electrically conductive plate 211 is formed as a pattern on the metal layer of a circuit board 22, it can be formed in any optional configuration. Thus the electrically conductive plate 211 and the slot 212 are of L-shape form with an angle 213g so that one leg is longer than the other leg.

The configuration of the electrically conductive plate 211 can be designed according to a configuration for a portable wireless set case. For instance, the electrically conductive plate 211 can be a rectangle or can have a circular outer periphery, if it is not L-shaped.

As the antenna body 2 1 h is part of the circuit board 22, the device can be miniaturised and thinned. Especially when the outer peripheries of the circuit board 22 and the electrically conductive plate 211 are circular, the device is appropriate for being contained in a circular wristwatch case. As the electrically conductive plate 211 is a conductor pattern, a tuning capacity element in the form of a capacitor 211 can be mounted on the top of the electrically conductive plate 211 across the slot 212.

It is also possible to make use of through-holes formed in the circuit board 22 electrically to connect the electrically conductive plate 211 and the reflecting plate 214. The reflecting plate 214 is opposed to the electrically conductive plate 211 with a more than equal area, and ground electric potential is applied thereto.

First variant of the fourth embodiment In a first variant (Fig. 16) of the fourth embodiment, only the reflecting plate 214 is formed as a conductor pattern on the circuit board 22. The electrically conductive plate 211 is fixed on the circuit board 22 on the opposite face to form an antenna body 21i. The electrically conductive plate 211 has terminals 21 la to 21 ld on the outer peripheral sides and the terminals 21 la to 21 ld are soldered on conductor patterns of the circuit board 22. It will be appreciated that the reflecting plate 214 may alternatively be separately formed and fixed to the circuit board 22 and the plate 211 be formed of a conductor pattern thereon.

16 If a multi-layer board having four or six metal layers is employed, the electrically conductive plate and/or the reflecting plate can be composed of any of these metal layers.

Fifth embodiment In a fifth embodiment (Fig. 17) of slot antenna device according to the present invention, an antenna body 3 la has a first rectangular electrically conductive plate 32 and a second rectangular electrically conductive plate 33 parallel and spaced by a gap 34. As electrically conductive material, metal can be employed, for example in the form of a thin film deposited inside a plastic case of a portable wireless set. The material is not limited as long as it has high electrical conductivity.

The first and second electrically conductive plates 32 and 33 are electrically connected by a short circuit plate 35 at an edge portion on one side, and at another edge portion, a wireless set circuit block 36 in which a wireless set circuit is formed is electrically connected at feed points 37a and 37b.

The antenna body 31a formed in this way has, on the outer peripheral side of the first and second electrically conductive plates 32 and 33, a slot 342 formed by the gap 34 starting from the forming position of the short circuit plate 35, passing through the outer periphery of the first and second electrically conductive plates 32 and 33 and returning to the short circuit plate 35, and functions as a slot antenna.

Furthermore, the slot 342 is open in every direction with the width corresponding to the gap 34 between of the first and second electrically conductive plates 32 and 33. Accordingly, compared with a slot antenna in which a slot extending C straight is formed, in the antenna body 31a of this embodiment a loop antenna mode is C available. Therefore both electromagnetic components are effectively received or transmitted, and the antenna body 31a has high antenna gain.

0 The directivity characteristics (Fig. 18) of the antenna body 31a with the slot 0 342 bent in a rectangle are shown by a solid line A 1, and may be compared with the 0 directivity characteristics shown by a dotted line A2, of a slot antenna with a slot of the same size extending straight. Each value is shown by a relative ratio to the maximum 17 value of the antenna gain, and is a directivity on a horizontal plane. Comparing these directivity characteristics, the antenna body 3 1 a of this fifth embodiment has antenna gain improved by several decibels over that of the slot antenna for comparison. The antenna body 3 la also has a pattern of directivity characteristics rounder than that for the slot antenna for comparison, with the null point on the decrease and nearly isotropic. Accordingly, the antenna body 3 la of the fifth embodiment can be thinned and also is highly sensitive, therefore it is appropriate for a portable wireless set.

For the purpose of reinforcing the antenna body 31a, plastics material or the like can be inserted in the gap 34. Particularly, if a dielectric material with low loss is inserted in the gap 34 to fill the slot 342, the wavelength of received electromagnetic waves can be apparently shortened. Consequently, even if the antenna body 3 la is small-sized, it can receive electromagnetic waves with relatively long wavelength. Furthermore, antenna gain can be improved without enlarging the antenna body 31a.

By setting the position of the feed points 37a and 37b in an optimum position considering the impedance matching of the antenna body 31a and the wireless set circuit block 36, high sensitivity can be obtained. The short circuit part 35 can have any structure. For example, it can be made from integral parts of the plates 32 and 33, from an integral part of one of the plates 32 and 33, from a part integral with both plates 32 and 33, or from a part separate from both plates 32 and 33. If the latter, it can be fixed on the electrically conductive plate by screws, bolts or the like or by welding or the like.

First variant of the fifth embodiment In a first variant (Fig. 19) of the fifth embodiment, an antenna body 31b is formed from a first rectangular electricall conductive plate 32 and a second rectangular y electrically conductive plate 33 parallel and spaced by a fixed gap 34, with a short circuit plate 35 formed to connect electrically the first and second electrically conductive plates 32 and 33 at an edge portion on one side.

18 A tuning capacitance element 38 is electrically connected between the first and second electrically conductive plates 32 and 33 across the slot 342 at an edge portion on the opposite side of the plates to the short circuit plate 35. This connecting position corresponds to the position in which the tuning capacitance element 38 is electrically connected with the antenna body 31b at the lengthwise centre of the slot 342.

The tuning capacitance element 38 makes the antenna body 3 lb tune even if the outer peripheral size of the first and second electrically conductive plates 32 and 33, that is, the length of the slot 342, is shorter than the size corresponding to half the wavelength of frequency used. Furthermore, the tuning capacitance element 38 is placed in the lengthwise centre of the slot 342 to maximise antenna gain. As shown in Figure 20(a), in the antenna body 3 la not employing a tuning capacitance element, because the amplitude I of an electric current generates a sine wave, the antenna body resonates when half wavelength and the length of the slot 342 coincide. On the other hand, as shown in Figure 20(b), in the antenna body 3 1 b having the tuning capacitance element 38 in the lengthwise centre of the slot 342, the amplitude I of an electric current is changed suddenly by the tuning capacitance element 38, so that wavelength is apparently shortened. If the tuning capacitance element 38 is placed in the centre of the slot 342, electric current can be balanced on both sides. Accordingly, maximum electric current can be applied to the antenna body 31b to improve the antenna gain.

Second variant of the fifth embodiment In a second variant (Fig. 2 1) of the fifth embodiment, an antenna body 3 1 c has feed points 371a and 372b to the circuit block 36 on the same edge portion side as connection points 38a and 38b for the tuning capacitance element 38. As the feed points 371a and 372b and the connection points 38a and 38b are side by side, the tuning capacitance element 38 can be mounted in the wireless set circuit block 36 together with wireless set circuitry. Accordingly, the number of parts in assembly can be decreased and the structure can be simplified, hence a reduction of cost.

Third variant of the fifth embodiment 19 In a third variant (Fig. 22) of the fifth embodiment, an antenna body 31d has the outer peripheries of the first and second electrically conductive plates 32 and 33 bent towards each other to form side portions 321 and 331. The slot 342 is formed by the gap 34a between the lower edge of the side portion 321 and the upper edge of the side portion 331.

In the antenna body 3 1 d formed in this way, the width of the gap 34a and thus of the slot 342, determines antenna gain. When the frequency used is high short wavelength, the width of the slot 342 needs to be reduced, and if the frequency used is 100 MHz, the appropriate width of the slot 342 is about 5 to 9 mm. If the frequency used is 300 MHz, the appropriate width of the slot 342 is about 3 to 7 mm. The width of the slot 342 can be adjusted, without changing the basic design in the antenna body 31d, to an appropriate value for the tuning frequency by establishing the side portions 321 and 331 in the first and second electrically conductive plates 32 and 33 without changing the opposition distance of the first and second electrically conductive plates 32 and 33, and by changing the width. Accordingly, the tuning frequency can be changed without changing the design of a case for a wireless set main body to contain the first and second electrically conductive plates 32 and 33 and so on, a member to fix the first and second electrically conductive plates 32 and 33 and so on.

Fourth variant of the fifth embodiment In a fourth variant (Fig. 23) of the fifth embodiment, a wireless set circuit block 36 is placed between a first electrically conductive plate 32 and a second electrically conductive plate 33, but is not placed outside the antenna body 31d. Consequently, there is no need to secure the space for the wireless set circuit block 36. Hence the miniaturisation of the portable wireless set is enhanced.

Fifth variant of the fifth embodiment In a fifth variant (Fig. 24(a)) of the fifth embodiment, an antenna body 3 1 e has a rectangular aperture 320 in the centre of the first electrically conductive plate 32, and a rectangular aperture 330 in the centre of the second electrically conductive plate 33. The portable wireless set is miniaturised by placing a wireless set circuit block 36 in the centre between the first electrically conductive plate 32 and the second electrically conductive plate 33. The position of the apertures 320 and 330 corresponds to the position of the wireless set circuit block 36. As the apertures 320 and 330 are bigger than the area the wireless set circuit block 36 occupies, the upper and lower sides of the wireless set circuit block 36 are open.

In the antenna body Me formed in this way, because the wireless set circuit block 36 is between the first and second electrically conductive plates 32 and 33, the first and second electrically conductive plates 32 and 33 easily catch the noise the wireless set circuit block 36 generates. In this embodiment, as the apertures 320 and 330 are formed in the position corresponding to the wireless set circuit block 36, the electric field occurring between the first and second electrically conductive plates 32 and 33 concentrates on the outside of the conductive plates 32 and 33, and does not occur near the wireless set circuit block 36. Consequently, as the noise generated by the wireless set circuit block 36 does not disturb the electric field occurring between the first and second electrically conductive plates 32 and 33, there is little noise influence and antenna gain improves.

For instance, the directivity characteristics of the antenna body Me is measured by using an antenna device itself, as shown by a dotted line B2 in Figure 24(b). When t:l the antenna body 3 1 e is put in a breast pocket, the directivity characteristics is shown by a solid line Bl. Each value is shown by a relative ratio to the maximum value of the antenna gain and is a directivity on a horizontal plane. Comparing these characteristics is, the image effect of a human body improves antenna gain several dB in front of human body (00 direction), therefore it is suitable for a portable wireless set such as a pager and so on.

If a liquid crystal display panel 361 (Fig. 24(a)) is put on the top of the wireless set circuit block 36 and information is displayed there, the information can be seen through the aperture 320 of the first electrically conductive plate 32. As the aperture 330 of the second electrically conductive plate 33 opens the bottom of the wireless set 21 circuit block 36, it is easy to exchange a battery fitted inside the wireless set circuit block 36. Consequently, a wristwatch-type portable wireless set as shown in Figure 25 can be constituted using the antenna body 31e. This wristwatch-type portable wireless set has an aperture 390 as a display on the surface of a case 39. Wrist straps 391 and 392 are connected to either side of the case 39. After the first electrically conductive plate 32, the wireless set circuit block 36, and the second electrically conductive plate 33 are sequentially contained in the case 39, the back of the case 39 is covered with a bottom cover 393 to form a wristwatch-type portable wireless set.

In the wristwatch-type portable wireless set formed in this way, the information displayed on the display such as the liquid crystal display panel formed on the top of the wireless set circuit block 36 can be seen through the aperture 390 of the case 39 without being obstructed by the first electrically conductive plate 32. As the antenna body 31e is completely covered with the case 39 and the bottom 393, there is no need to consider resistance to corrosion, resistance to abrasion and so on of the material to constitute the antenna body 31e. Accordingly, the antenna body 31e can be composed of a metal material with low resistance to corrosion but with high electrical conductivity such as copper to improve antenna gain.

Sixth variant of the fifth embodiment In a sixth variant (Fig. 26) of the fifth embodiment, an antenna body 3 1 f of a portable wireless set is formed of a first electrically conductive plate 32 and a second electrically conductive plate 33 opposed to each other across a slot. The first electrically conductive plate 32 having an aperture 320 in the centre serves as part of a case for a wristwatch-type portable wireless set, and the second electrically conductive plate 33 serves as a bottom cover to cover the back of the case. Accordingly, there is no aperture in the centre of the second electrically conductive plate 33, but the wireless set circuit block 36 can be easily removed through the back of the case.

The bottom edge of the side portions 325 of the first electrically conductive plate 32 are cutout at 329 except for a short circuit portion 35 left in the edge 326. In the 22 cutout 329 a spacer 327 composed of an electrically insulating material such as a plastics material is fixed. Accordingly, when the back of the first electrically conductive plate 32 is covered with the second electrically conductive plate 33 after the wireless set circuit block 36 is contained inside the first electrically conductive plate 32, a slot is provided between the plates 32 and 33 because there is the spacer 327 between them. The first electrically conductive plate 32 and the second electrically conductive plate 33 are electrically connected by the short circuit portion 35. Accordingly, in this variant, the antenna body 3 1 f having the first electrically conductive plate 32, the spacer 327 and the second electrically conductive plate 33 functions as a slot antenna.

In a wristwatch-type portable wireless set formed in this way, information displayed on display device such as a liquid crystal display panel formed on the top of the wireless set circuit block 36 can be seen through the aperture of the first electrically conductive plate 32.

In this sixth variant, the antenna body 31f and the wireless set circuit block 36 constitute a circuit shown in Figure 27(a). In order to carry out unbalanced feed to the antenna body 31f, a feed point 371a of the first electrically conductive plate 32 is electrically connected with a feed circuit 361 of the wireless set circuit block 36 through an antenna terminal 373, and a feed point 372b of the second electrically conductive plate 33 is electrically connected with a ground terminal 362 of the wireless set circuit block 36. In such a connection structure, by changing the set position of the feed points 371a and 372b at the outer periphery of the first and second electrically conductive plates 32 and 33 and setting the distance between the feed points 371a and 372b and the tuning capacity element 38 at optimal conditions, impedance matching between the antenna body 31f and the wireless set circuit block 36 can be realised.

On the other hand, in order to carry out balanced feed to the antenna body 31f, a circuit shown in Figure 27(b) is constituted. In this circuit, a feed point 371a of the first electrically conductive plate 32 is electrically connected with a feed circuit 361 of the wireless set circuit block 36 through an antenna terminal 373, and a feed point 372b 23 of the second electrically conductive plate 33 is electrically connected with a feed circuit 361 of the wireless set circuit block 36 through an antenna terminal 374. In such a connection structure, too, by changing the set position of the feed points 371a and 372b at the outer periphery of the first and second electrically conductive plates 32 and 33 and setting the distance between the feed points 371a and 372b and the tuning capacitance element 38 at optimal conditions, the impedance matching between the antenna body 31f and the wireless set circuit block 36 can be realised.

Sixth embodiment In a sixth embodiment (Fig. 28), an antenna body 41a has a first electrically conductive plate 42 and a second electrically conductive plate 43 placed parallel and spaced by a fixed gap 44, and the first and second electrically conductive plates 42 and 43 are electrically connected by a short circuit 45 at an edge portion on one side. The antenna body 41 a has a slot 442 formed at the outer periphery of the first and second electrically conductive plates 42 and 43 by the gap 44 extending from the short circuit 45 through the outer periphery of the first and second electrically conductive plates 42 and 43 back to the short circuit 45. Consequently, the antenna body 41a functions as a slot antenna.

The first and second electrically conductive plates 42 and 43 are composed of conductor patterns on the outer peripheral sides made by patterning metal layer (e.g. copper) layers formed on both sides of a circuit board 47 which is a two-sided copperclad glass epoxy laminate. Accordingly, the gap 44 is the glass epoxy of the circuit board 47, and the short circuit 45 is a build-up formed inside through-holes 471 of the circuit board 47.

A tuning capacitor element 48 is mounted on and electrically connected to the first electrically conductive plate 42 and to a conductor pattern 472 formed inside the first electrically conductive plate 42 on the surface of the circuit board 47. Another conductor pattern 473 is formed inside the second electrically conductive plate 43 at the back of the circuit board 47. The conductor patterns 472 and 473 are electrically 24 connected through a build-up formed inside a through-hole 474 of the circuit board 47. Thus the tuning capacity element 48 is mounted across the first electrically conductive plate 42 and the conductor pattern 472 on the surface of the circuit board 47. The tuning capacitance element 48 may be a chip capacitor, varactor diode or the like, and is electrically connected between the first and second electrically conductive plates 42 and 43 across the gap 44. The connection position of the tuning capacitance element 48 is opposite the short circuit 45 and corresponds to the lengthwise centre of the slot 442.

In the antenna body 41a formed in this way, the first and second electrically conductive plates 42 and 43 can be of an optional configuration by patterning the metal layer on the both sides of the circuit board 47, and the width of the gap 44 and slot 442 is uniform. The slot width can be correctly designed with the thickness of the circuit board 47. As a thin antenna body 41a can be formed, it is suitable for insertion into a portable wireless set, such as a pager. The tuning capacitance element 48 can be mounted in the same way as electronic parts constituting the wireless set circuitry. Furthermore, as the first and second electrically conductive plates 42 and 43 conductor patterns patterned along the outer periphery edge of the circuit board 47, the slot is long and the wireless set circuitry can be placed inside.

First variant of the sixth embodiment In a first variant (Fig. 29), of the sixth embodiment, an antenna body 41b has first and second electrically conductive plates 42 and 43 composed of a conductor pattern made by patterning a metal layer formed on both sides of a circuit board 47. The glass epoxy base of the circuit board 47 fills the gap 44 as a slot 442 and extends outside the area of the plates 42 and 43.

The first and second electrically conductive plates 42 and 43 are formed in the left half 47a of the circuit board 47, and the right half 47b carries wireless set circuitry. A conductor pattern 475 is formed in the boundary between the right half 47b and the left half 47a, and a coupling capacitor 491 is mounted to the conductor pattern 475 and the first electrically conductive plate 42.

The coupling capacitor 491 (Fig. 30) electrically connects the antenna body 41b and a transistor 490 operating as an amplification circuit in the first stage of the wireless set circuitry. The connection position (feed point) of the coupling capacitor 491 and the antenna body 41b is located approximately centrally between the formation position of the short circuit 45 and the connection position of the tuning capacity element 48, and performs impedance matching between the antenna body 41b and the wireless set circuitry.

As the antenna body 41b formed in this way is formed in the area distant from the wireless set circuitry, including transistor 490 on the circuit board 47, it is not influenced by noise generated by the wireless set circuitry.

Second variant of the sixth embodiment In a second variant (Fig. 31 & 32) of the sixth embodiment, an antenna body 4 1 c has a first conductor pattern 42a and a second conductor pattern 43a formed by patterning a metal layer formed on each side of the glass epoxy base of a circuit board 47 which fills a gap 44 between the patterns to act as a slot 442. First and second rectangular electrically conductive plates 42b and 43b are soldered on the top of the first and second conductor patterns 42a and 43a. Accordingly, in the antenna body 41c, the first conductor pattern 42a and the first electrically conductive plate 42b are united to form one conductor, and the second conductor pattern 43a and the second electrically conductive plate 43b are united to form one conductor. Consequently, in this variant, the electrical conductivity of the first and second electrically conductive plates 42b and 43b contributes to a reduction in resistance and the loss of the antenna body 41c is reduced and the sensitivity improves. Although, as shown, the first and second electrically conductive plates 42b and 43b have a part cut out, they can be complete loops.

Seventh embodiment In a seventh embodiment (Fig. 33), a slot antenna is composed of a circuit board and a conductor separate from the circuit board.

26 In an antenna body 5 1 a first and second metal wires 52 and 53 as conductors are soldered on conductor patterns 541, 542 and 543 formed on either side of a base 54 of a circuit board. Accordingly, there is a gap 55 formed between the first and second metal wires 52 and 53. In the conductor pattern 543, a short circuit 56 to electrically connect the first and second metal wires 52 and 53 is composed of a build-up formed inside through-holes 540 of the circuit base 54.

Consequently, as shown in Figure 34, because a slot 550 is formed in the path from the short circuit 56 between the first and second metal wires 52 and 53 and back again to the short circuit 56, the antenna body 5 la functions as a slot antenna.

0 A tuning capacitor 57 is mounted between the conductor pattern 541 (Fig. 33) and an adjacent conductor pattern 545. A coupling capacitor 58 is mounted between the conductor pattern 542 and an adjacent conductor pattern 544. The coupling capacitor 58, (Fig. 34) is electrically connected with a transistor 59 of an amplification circuit 5 of wireless set circuitry through the conductor pattern 544 (Fig. 33).

As the antenna body 5 la is composed of conductor patterns 541 and 542 on the base 54 and the through-holes 540, the antenna body 5 la can be easily fixed and electrically connected.

Eighth embodiment In an eighth embodiment (Fig. 35), an antenna body 61a is composed of first and second rectangular frame-shaped electrically conductive plates 62 and 63. In this case, too, first and second electrically conductive plates 62 and 63 are soldered on conductor patterns 641, 642 and 643 of a glass epoxy base 64 of a circuit board. A tuning capacitance element 65 and a coupling capacitor 66 are electrically connected with the first and second electrically conductive plates 62 and 63 through respective conductor patterns 644 and 645 formed adjacent to the conductor patterns 641 and 642. A short circuit 68 to electrically connect the first and second electrically conductive plates 62 and 63 is composed of a build-up formed inside through-holes 640 formed in the circuit board base 64.

27 Side portions 621 and 631 are formed in the first and second electrically conductive plates 62 and 63, respectively, and the side portions 621 and 631 are soldered on the conductor patterns 641 and 642. Accordingly, as a gap is secured between the circuit board 64 and thefirst and second electrically conductive plates 62 and 63, the tuning capacity element 65 and the conductor pattern 644 as well as other components can be placed inside.

First variant of the eighth embodiment In a first variant (Fig. 36) of an eighth embodiment, an antenna body 61b is composed of first and second electrically conductive plates 62 and 63 having side portions 621 and 631, from which terminals 62a to 62c and 63a to 63c of the same length project. The terminals 62a to 62c and 63a to 63c are soldered on conductor patterns 641, 642 and 643, respectively, which are formed in circuit board base 64.

Accordingly, in the antenna body 61b in this embodiment, a slot of the width of the thickness of the circuit board base 64 plus the length of the terminals 62a to 62c and 63a to 63c is formed. Consequently, the width of the slot can be changed by changing the length of the terminals 62a to 62c and 63a to 63c.

C The rieffit half of the circuit board base 64 is left as a space in which to constitute wireless set circuitry. However, as the terminals 62a to 62c and 63a to 63c expand the space between the first and second electrically conductive plates 62 and 63 and the circuit board base 64, the wireless set circuitry can be formed inside the first and second electrically conductive plates 62 and 63 making use of this space, without establishing the above-mentioned right half blank space.

Second variant of the eighth embodiment In a second variant (Fig. 37) of the eighth embodiment, when the first and second electrically conductive plates 62 and 63 are composed only of parts corresponding to the side portions 621 and 631 and have a rectangular frame shape. It is thus possible to fix the first and second electrically conductive plates 62 and 63 on the circuit board base 64 and the slot width can be adjusted by making use of the terminals 28 62a to 62c and 63a to 63c. In this variant, too, the wireless set circuit block can be placed inside the first and second electrically conductive plates 62 and 63, and a liquid crystal display panel and so on can be formed on the top of the wireless set circuit block to display information.

Third variant of the eighth embodiment In a third variant (Fig. 38) of the eighth embodiment, the side portion 621 and the terminals 62a to 62c are formed only in the first electrically conductive plate 62 having an aperture 620 approximately in the centre, the second electrically conductive plate 63 being formed as a plane plate. In this variant, too, the slot width can be adjusted by the length of the terminals 62a to 62c on the side of the first electrically conductive plate 62.

Ninth embodiment In a ninth embodiment, (Fig. 39) of antenna body, a ceramic circuit board 74 on both faces of which first and second metal layers 72 and 73 are formed, is employed in an antenna body 71a and a slot 276 is formed around the sides 741. A short circuit 75 to conductively connect the first and second metal layers 72 and 73 is formed in the lengthwise centre of the side 741 of the ceramic circuit board 74.

The antenna body 71a formed in this way can be easily miniaturised and thinned because the normal ceramic circuit board 74 can be cut in fixed size and the short circuit 75 can be composed of an electrically conductive coating layer, a build-up in a through hole or a deposit on the side 741. As the slot 76 is filled with the substrate material of the ceramic board base 74, the received wavelength can be apparently shortened. Accordingly, a small-sized antenna body can receive electromagnetic waves with relatively long wavelength.

First variant of the ninth embodiment.

In a first variant (Fig. 40) of the ninth embodiment, the antenna body has side portions 721 and 731 of the layers 72 and 73 formed using an electrically conductive coating layer, a build-up, or a deposit or the like on the side portion 741 of the ceramic 29 board base 74 in such a way as to connect from the first and second metal layers 72 and 73. The gap between the side portions 721 and 731 can be used as a slot 76. In this case, the width of the slot 76 can be adjusted by adjusting the width of the side portions 721 and 731, and there is no need to change the thickness of the ceramic board 74.

Second variant of the ninth embodiment In a second variant (Fig. 41) of the ninth embodiment, it is possible to form a first metal layer 72 only on an edge portion of the ceramic circuit board 74, without leaving a metal layer in the centre. In this case, a conductor pattern 742 to connect with the first metal layer 72 and a conductor pattern 744 adjacent to the conductor pattern 742 are formed on the surface of the ceramic circuit board 74, and a conductor pattern 743 to connect with the second metal layer 73 is formed at the back of the ceramic circuit board 74. The conductor pattern 743 is electrically connected with the conductor pattern 744 through a build-up in a through-hole 740. A tuning capacity element 78 can be electrically connected with the first and second metal layers 72 and 73 across the slot 76 by mounting the tuning capacity element 78 to the conductor patterns 741 and 744.

As antenna body 71c formed in this way is a small-sized chip-like antenna body, it can be put in a small circuit base as it is. Consequently, the antenna body 71c is appropriate for a miniaturised and thinned portable wireless set.

Other embodiments In addition to the before-mentioned embodiments and their variants it is possible to combine features of each of them. For instance, the circuitry illustrated in Figures 2 and 3 can be combined not only with the antenna body according to the first embodiment, but also with any embodiments or variants thereof.

As explained above, in the present invention, a slot antenna device of the built-in type having a slot antenna body with an electrically conductive plate in which a slot opens has a circuit board inserted in the slot. Consequently, according to the present invention, the antenna body, being a slot antenna, is sensitive to magnetic components, and can be expected to have improved sensitivity when mounted on a human body. Accordingly, the antenna body is appropriate for a portable antenna- using device such as a pager. As the circuit base is inserted in the slot, as when a dielectric material is filled, the wavelength of received signals can be apparently shortened. Accordingly, even a small-sized antenna body can receive electromagnetic waves with relatively long wavelength.

If an electrically conductive plate is bent in a plane direction, a slot can be opened in two to four directions with an antenna body miniaturised and thinned, giving improved directivity characteristics.

If an electrically conductive plate is opposed to the surface of a circuit base in a slot antenna device having a slot antenna body with an electrically conductive plate in which a slot opens, the antenna device can be thinned.

Furthermore, in a slot antenna device having a slot antenna body with an electrically conductive plate in which a slot opens, a reflector may be placed at the back of the electrically conductive plate and can improve sensitivity with the device miniaturised and thinned.

According to the present invention, if an electrically conductive plate is composed of a conductor pattern formed on the surface of a circuit board, the number of parts to realise miniaturisation can be reduced.

In another form of the present invention, a slot antenna body is formed making use of a pair of electrically conductive plates opposed to each other across a gap to be a slot at the outer periphery. Consequently, according to the present invention, a thin antenna body can be constituted and an antenna body with improved directivity can be formed because the slot opens toward the outer periphery.

If an aperture is formed corresponding to the formation area of a wireless set circuit in an electrically conductive plate, the display on a display panel formed on the top of the wireless set circuit can be seen through the aperture of the electrically t> conductive plate even if it is employed as a case main body.

31 If the electrically conductive plates are formed on the front and back surfaces of a circuit board in which wireless set circuitry is formed, the antenna body can be thinned and the thickness of the circuit board can be set at the slot width correct to the standard. In this case, the electrically conductive plates can be composed of a conductor pattern formed on the surface of the circuit board to decrease the number of parts.

The aforegoing description has been given by way of example only and it will be appreciated by a person skilled in the art that modifications can be made without departing from the scope of the present invention.

32

Claims

1. A device comprising an electrically conductive member formed with a slot therethrough to form a slot antenna, and a circuit board carrying wireless circuitry for connection to the antenna, wherein the electrically conductive member is contiguous with the surface of the circuit board.

2. A device according to claim 1, wherein the electrically conductive member has terminals on the periphery of the slot projecting downwardly to engage the surface of the circuit board.

3. A device according to claim 2, wherein the electrically conductive member has a downwardly depending lip at least at one end to space the member from the circuit.

0

4. A device according to claim 1, wherein the electrically conductive member is bent about a line transverse to the slot at two bend points, and is mounted on the circuit board to extend around the periphery thereof so as to be located adjacent both surfaces of the circuit board.

5. A device according to claim 4, wherein the electrically conductive member has a downwardly depending lip at least at one end to engage the surface of the circuit board 1:1 k:' 0 and space the member therefrom.

6. A device according to any preceding claim, wherein a reflector is mounted to be spaced from the slot and substantially parallel thereto.

7. A device according to claim 6, wherein the space between the reflector and the slot antenna is filled with dielectric material.

33

8. A device according to claim 7, wherein the slot is filled with dielectric material.

9. A device according to claim 6 or claim 7, wherein the circuit board is mounted in the slot of the antenna.

10. A device according to claim 6, wherein the circuit board is mounted in the space between the reflector and the slotted member.

11. A device comprising a circuit board carrying wireless circuitry for connection to an antenna and an electrically conductive member with a slot to form a slot antenna, both formed in the circuit board as a single conductive pattern.

12. A device according to claim 11, including a reflector which is larger in area than the electrically conductive member and is spaced from the member.

13. A device according to claim 12, wherein the reflector is formed as a conductor pattern of the circuit board.

14. A device to claim 13, wherein the circuit board is a multi-layer board and the electrically conductive member and reflector are formed by conductor patterns on two of the plurality of layers.

15. A device according to any one of claims 11 to 14, wherein the slot in the conductive pattern is bent into an L-shape.

16. A device according to any one of claims 11 to 14, wherein the slot in the C.

conductive pattern is bent into a substantially rectangular shape.

34

17. A device according to any one of claims 11 to 14, wherein the slot in the conductive pattern is of substantially circular shape.

18. A device according to any one of claims 11 to 17, wherein a tuning capacitor is mounted across the slot.

19. A device according to any preceding claim, wherein the antenna has a feed point with terminals of the wireless apparatus composed of an unbalanced circuit, and another feed point with a ground terminal of the apparatus.

20. A device according to any of claims 1 to 18, wherein the antenna has a feed point with two terminals of the wireless apparatus composed of a balanced circuit.

21. A wireless apparatus including a device according to any preceding claim.

22. A slot antenna device substantially as hereinbefore described with reference to and/or as illustrated in any one of figures 8 to 12, 15 and 16 of the accompanying drawings.